Current blow-molding machinery is designed to manufacture hollow plastic containers by extruding a parison between opposed, parted mold halves. The mold is then closed and air is injected into the parison, blowing and distending it outward so that it conforms itself to inner contours of the mold that complement the outer shape of the bottle to be produced. Once the distended parison has hardened into a container, a take-out mechanism extracts the newly formed container from the mold.
Some plastic bottle manufacturers produce blow-molded articles by using rotary blow-molding machines. A typical rotary blow-molding machine includes a rotating mold carrousel that carries two or more mold stations around a circular mold station path. Each mold station includes a mold with a mold cavity. The mold carrousel is indexed to hold each mold station momentarily motionless at each of a series of blow molding "work stations". A "work station" is a position where each mold station must pause in its circular path for a particular operation to be carried out. A "work station series" is a progression of work stations necessary to complete a blow molding process on a single mold station in a single mold carrousel revolution. Blow molding operations are carried out sequentially on each mold as each mold station rotates through a work station series, pausing momentarily at each work station in the series.
Rotary blow-molding machines may include any number of mold and work stations, and may include more than one work station series arranged around a single mold station path.
The final work station in a work station series is the article take-out work station. It is at this work station that an article take-out mechanism releases or extracts the blown articles from their respective molds. An article take-out mechanism can be configured to remove articles from molds while the molds are paused momentarily at the article take-out work station. Alternatively, an article take-out mechanism can be configured to remove articles "on the fly" as each mold passes the article take-out work station, i.e., without pausing mold carrousel rotation.
An example of the latter of those two types of take-out mechanisms that removes articles "on the fly" is shown in U.S. Pat. No. 4,902,217 (the '217 patent) issued to Martin et al. This patent discloses a rotary take-out mechanism with an oscillating turret arm mounted adjacent a mold carrousel at an article take-out work station. One end of the turret arm is pivotally mounted to a mold carrousel axle. The other end of the turret arm, i.e., the "outer" end, extends radially outward from the mold carrousel axis beyond the mold carrousel outer diameter. A take-out member is mounted on the turret arm outer end. As the molds revolve around the mold carrousel axle, the turret arm repeatedly swings the take-out member upward and downward through a small arcuate path just outside the circular path of the molds as the molds pass the take-out work station. The downward swing of the turret arm matches the movement of the orbiting molds thus canceling relative motion between the molds and the take-out member over a small arcuate distance. This temporary lack of relative motion provides enough time for the take-out member to engage and extract blown articles from the molds as they pass the take-out work station.
The take-out member of the Martin et al. patent comprises four pneumatically actuated article-engagement members mounted at spaced locations around the circumference of a take-out carrousel. The article-engagement members are individually supplied with pressurized air through separate pneumatic feeds. The feeds are separated by channels in the hub. This allows a controller mounted off the carrousel to sequentially direct pressurized air to each article engagement member through the separate pneumatic feeds through the hub and a rotary union that channels air into the hub from the controller. The take-out carrousel is rotatably mounted at the turret arm outer end on an axis parallel to that of the mold carrousel axis. The take-out carrousel is synchronized to rotate in an angular direction opposite that of the mold carrousel. As each article-engagement member rotates past a mold carrousel mold it engages a blown article, removes it from its mold, rotates it downward and away from the mold carrousel, and places it in an upright position on an article-conveyor mechanism.
Take-out mechanisms of the type disclosed in the Martin et al. patent are inherently complex as they must synchronize with and track the continuous arcuate motion of the molds as the molds pass an article take-out work station. In addition, it takes considerable energy to repeatedly reverse the path of a turret arm that carries a take-out carrousel as described in the Martin et al. patent. Still further, the separate pneumatic feeds complicate the structure of the hub and rotary union.
Another example of a rotary take-out apparatus for removing blow-molded articles "on the fly" from a non-indexed, continuously rotating mold is disclosed in the Bilodeau U.S. Pat. No. 3,981,667 (the Bilodeau patent). The Bilodeau take-out apparatus includes a vertically-oriented rotatably-mounted take-out carrousel with three pick-up stations disposed at circumferentially-spaced locations on the take-out carrousel. A rotary union channels air through a hollow hub portion of the take-out carrousel to the pick-up stations. Pneumatic hoses channel the air from the hub to air valves located at each of the take-out stations. Each air valve provides air pressure to pick-up heads at each pick-up station.
However, the Bilodeau apparatus is unable to use pneumatic pressure to drive its pick-up heads in and out. Instead, it requires mechanical interaction between a journalled roller and a stationary cam slot mounted adjacent the take-out carrousel. In addition, the Bilodeau pick-up heads comprise suction cups that cannot attach to the open end of a blow-molded article. Instead, the suction cup pick-up heads disclosed in Bilodeau are provided with negative air pressure (a vacuum) to attach via suction to flat, smooth outer surfaces of newly blow-molded articles. In addition, the air valves disclosed in Bilodeau for supplying negative air pressure to the pick-up heads cannot be electrically actuated and instead rely on mechanical actuation through the above-described interface of a roller with a stationary cam slot. Moreover, the Bilodeau patent discloses no structure capable of supplying electrical power or signals to components mounted on the take-out carrousel. Still further, the Bilodeau patent discloses no structure capable of extending and retracting the pick up heads or operating the air valves while the carrousel is not moving.
What is needed is a rotary take-out apparatus that does not require an oscillating turret arm or similar structure to provide synchronized motion to allow the apparatus can engage and remove blow-molded articles from a rotary blow-molding machine. What is also needed is such an apparatus that does not require carrousel rotation or mechanical interaction between components mounted on the carrousel and components mounted off the carrousel to provide reciprocal pick-up head motion and to sequence air valves that actuate pick-up heads.